Production of quaternary carbon-containing monoolefins by thermal dehydrohalogenation



United States Patent 3,227,770 PRODUCTION OF QUATERNARY CARBON-CONTAINING MONOOLEFINS BY THERMAL DEHYDROHALOGENATION Emmett H. Burk,Jr., Hazel Crest, and William D. Hoffman, Park Forest, Ill., assignorsto Sinclair Research, Inc., Wilmington, Del., a corporation of DelawareNo Drawing. Filed Dec. 26, 1962, Ser. No. 247,345 7 Claims. (Cl. 260677)This application is a continuation-in-part of parent application SerialNo. 94,956, filed January 11, 1961, now abandoned.

This invention relates to a process for the production of quaternarycarbon-containing monoolefins.

The quaternary carbon-containing monoolefins have recently been found tobe valuable al ha olefins for the production of polymers of high meltingpoint and polymers possessing other highly desirable characteristics.For example, it has been reported in Linear and Stereoregular AdditionPolymers, Gaylord and Mark, Interscience Publishers Inc., New York,1959, page 64 that isotactic poly-3,3-dimethyl-1-butene has beenproduced having a melting point of approximately 300 C. Also a copolymerof ethylene and 3,3-dimethyl butene-l has been made using a conventionalperoxide catalyzed polymerization process which copolymer ischaracterized by being more flexible and having an increase inextensibility of 300 to 500 percent over low density polyethylene. (SeeUS. Patent No. 2,728,752 to H. C. Brown.)

At the present time we have no knowledge of a commercially practicalprocess for the manufacture of quaternary carbon-containing monoolefinssuch as 3,3-di methyl tbutene-l. One of the reasons for this problem isthe extremely unfavorable equilibrium of these monoolefins in isomericmixture. In the case of 3,3-dimethyl butene-l, for instance, attemperatures of above 127 C. it is the least favored of the C olefinisomers. For example, dehydration of pinacolone alcohol leads to only a3% yield of 3,3-dimethyl butane-1 which is its equilibrium value in amixture of dimethylbutenes.

conventionally, 3,3-dimethyl butene-l is prepared by a long and involvedprocess which comprises dimerization of acetone by aluminum amalgam toform pinacol, rearranging the pinacol to pinacolone by treatment with anacid catalyst, reducing the pinacolone by catalytic methods to thecorresponding alcohol, i.e., 3,3-dimethyl- Z-butanol, forming a xanthateor other appropriate ester of the alcohol and subjecting it to thermalpyrolysis to obtain 3,3-dimethyl butene-l. 3,3-Dimethylbutene-1 has eenobtained by the pyrolysis of the stearic acid ester of 3,3-dimethylbutanol-2 (see Koch and Van Raay, BrennstoifChemie, 32, 161174, 1951).This process, however, causes skeletal re-arrangement to produce inaddition, the undesired isomer of the olefin, e.g.,2,3-dimethyl-l-butene and 2,3-dimethyl-2-butene. The isomer productionand the involved procedure of the process thus makes it an obviouslyunpractical method for the commercial production of3,3-dimethylbutene-1.

Dehydrohalogenation of halogen-hydrocarbons to produce olefins is notnew. The production of monoolefins from monohalogenated normal parafiinspresents no significant problem. In contrast, however, considerabledifiiculty is experienced in the dehydrohalogenation ofhalogen-substituted branched chain parafiins, particularly theneo-carrbon-containing halogenated hydrocarbons of the presentinvention. These latter structures on dehydrohalogenation have a strongtendency to undergo skeletal re-arrangement destroying in large part theneostructure and producing substantial amounts of isomers. For example,Louis Schmerling, in US. Patent No. 2,- 404,927 reported thedehydrochlorination of 1-chloro-3,3- dimethyl-butane but the product wasa mixture of olefins containing a new carbon structure, i.e., the methylgroups appeared in the 2,3 positions. The dehydrochlorination reactionof Schmerling was carried out in the presence of a catalyst undertemperatures ranging from 200 to 450 C.

We have now found a simple process of producing high selective yields ofquaternary carbon atom-containing monoolefins with essentially noskeletal isomerization to other olefins of similar carbon atom content.The process comprises dehydrohalogenating a select feed material underdefined reaction conditions.

The halogen hydrocarbon feed of the present invention may be representedby the structural formula:

wherein R is an aliphatic monovalent hydrocarbon radical such as a loweralkyl, including cycloalkyl, of up to 8 carbons, the total carbon atomsin all Rs being up to 18, preferably up to 12 and R may be branched orsubstituted with non-interfering groups; R is a divalent aliphatichydrocarbon radical of 2 to 8 carbons, preferably 2 to 4 carbon atoms;and X is a halogen atom having an atomic weight of 35 to 127. Preferablythe halogen is substituted on a carbon atom beta to the neocarbon atom.It is particularly preferred that the beta carbon atom be at an end ofthe carbon chain. Suitable feeds include, for instance,1-chloro-3,3-dimethylbutane; 1-chloro-3,3-dimethylpentane;2-chloro-4,4-dimethylpentane, etc.

In accordance with the present invention the feed in vapor form issubjected to a temperature of about 400 to 600 or even 650 C.,preferably 450 or 500 to 575 C. in a non-catalytic environment. Thus,the dehydrohalogenation can be satisfactorily effected in a nonpacked ortubular reactor as long as the reactors internal or contact surfaces arenon-catalytic or the dehydrohalogenation may be conducted in such areactor which contains non-catalytic, particulate contact material. Theterm particulate is meant to include, in addition to small individualforms such as beads, fragments, shavings, and like particles, othercontact forms such as helices, wire meshes, etc. It is important thatthe contacting surfaces and contacting environment, since they arenon-catalytic, be essentially free of acidic and basic materials, i.e.,be essentially neutral and remain so during the reaction. Similarly, toinsure a high selectivity in the dehydrogenation step, metals, metaloxides or other materials that may be present which react with hydrogenhalide to give basic or acid environments should be held to a minimum.Thus the environment is such as to avoid the presence of materials thatwould cause a significant amount of hydrogen halide ionization. Thesurface therefore may be non-polar or non-ionic as such or may become soduring the initial stages of reaction, which seems to be the case withthe high nickel-containing metal surfaces.

Suitable contact surfaces whether they be walls of the reactor orcontact materials in particulate form include for example, a quartz,Pyrex glass, ceramic, silica, coke, nickel and nickel alloys containingno more than about 40% iron, preferably less than about 20% or even lessthan about 10% iron. Included in the metal surfaces suitable for use inthe present invention are those containing a high nickel content,usually at least about 40% by weight and no more than the definedamounts of iron. Preferably the nickel content is at least about 50% oreven at least about 75%. Nickel alloys and other nickelcontainingmaterials having iron or other metals that react with hydrogen halidepresent in amounts greater than about 40% have been found unsuitable foruse in the present invention in that they effect substantialisomeriz-ation to isomers of the desired quaternary carbon-containingmonoolefins and consequently give a relatively poor selectivity to thedesired monoolefins for a given conversion. Metals other than iron thatare generally present in nickel alloys in minor amounts do not seem tohave a detrimental effect on the selectivity to the desired product ofthe present invention. Illustrative of a suitable nickel alloy isHast-Alloy C which is employed in Examples V and XI below. Hast-Alloy Cis composed of 50 to 60% Ni, 4.5 to 7% Fe, and minor amounts of Cr, W,Si, Mn, Cu, P and S. Another suitable nickel alloy is Monel metal whichis commonly composed of about 68% Ni, 31% Cu and 1% Fe.

When particulate contact materials are employed an LHSV (liquid hourlyspace velocity) of about 0.5 to 20, preferably about 2 to 10 isgenerally employed. The reaction can be carried out at atmospheric,subatmospheric or superatmosp'heric pressure and pressures in the rangeof about 50 to 150 p.s.i.g. are preferred. If desired an inert gas suchas nitrogen or carbon dioxide may be employed in the reaction and theinert gas can be in a ratio of about or 1 to 20 or more moles to 1 moleof hydrogen chloride produced. Under the conditions of the presentinvention the selectivity to the corresponding quaternarycarbon-containing monoolefin is greatly increased and no significantamounts of olefins of similar carbon content but without a neo-carbon,if any, are found in the crude product.

The feed of the present invention can be prepared by any method known tothe art. 1-chloro-3, 3-dimethylbutane, for example, can be prepared asdescribed by Louis Schmerling in the Journal of the American ChemicalSociety, 67, 11152 (1945). Briefly the process involves reacting onemole of ethylene with t-butylchloride using a Friedel-Crafts catalystsuch as AlCl FeCl BiCl or ZuCl The reaction can take place atatmospheric pressure when employing the reactive Friedel-Craftscatalysts such as A1013, advantageously at a temperature of about '1'5C. Under the conditions listed by Schmerling, i.e., complete conversion,the yield of 1-chloro-3,3-dimethylbutane was reported as 75% theory.Fractionation on a simple packed column generally furnishes a chlorideof sufficient purity for use in the present invention.

The following examples are included to further illustrate the presentinvention.

EXAMPLE I A Vycor reactor was packed with demagnetized tab alumina. Thisreactor was then heated to 480 C. with a stream of nitrogen passingthrough it. 1-chloro-3,3- dimethylbutane was introduced through acapillary from a calibrated reservoir. The reactor effluent wascondensed on a Dry Ice cold-finger condenser. The hydrogen-chloride wasswept out by the nitrogen into a sodium hydroxide trap. After a basewash, the reaction product was 5 analyzed by gas chromatography todetermine the relative amounts of the various olefin products. At acontact time of 2 seconds, a temperature of 480 to 500 C., the chloridewas found to yield an olefin mixture containing 19%3,3-dimethylbutene-l, 33% 2,3-dimethylbutene-l and 48%2,3-dimethylbutene-2. The yield of olefins was nearly quantitative.

In a second experiment at 530 C. and 1 second contact time, the ratio of2,3-dimethyl-l-butene to 2,3-dimethyl- Z-butene increased slightly.However, the yield of 3,3- dimethyl-butened did not increase,illustrating the unsuitability of tab alumina as a contact material.

EXAMPLE II A rock salt packing was substituted for the tab-aluminapacking in the previous experiment. A contact time of about 23 secondswas used. l-chloro-3,3-dimethylbutane was cracked at 4 differenttemperatures. At a temperature of 450 C., the olefin product consistedof the three dimethylbutene isomers in approximately the same yields asobtained over tab alumina. However, subsequent experiments at 530 C. and590 C. produced olefins in high yields with no isomerization of thecarbon chain. In these experiments, the only detectable C olefin presentwas 3,3-dimethyll-butene. It is believed that at the lower temperature(450 C.) the reaction over rock salt is primarily catalytic, as opposedto thermal, and causes isomerization, while at the higher temperatures(530 C. and 590 C.) the reaction effected is essentially thermal, withlittle if any isomerization being obtained. At the high temperature,some carbon-carbon cleavage occurred to yield isobutylene and other lowboiling compounds.

EXAMPLE III A Vycor reactor was packed with Pyrex beads. The reactor wasthen heated to 570 C. in an electrical furnace.:l-chloro-3,3-dimethylbutane was introduced along with prepurifiednitrogen as a diluent. The contact time was varied between 2 to 4seconds. The experiments were carried out as before. Below is a summaryof the results of these experiments.

Table I Percent 3,3- Experi- Feed 1 Contact Temp. Percentdiinethyl-lment time conversion butene in olefin cut 1 The same chloridewas used in all experiments. The number listed in column refers to thenumber of times the feed in this experiment had been subjected topyrolysis.

2 Some of the olefin was lost during distillation. This yield has beencorrected for that loss.

Following the last experiment, the recovered unreacted chloride wasexamined with the aid of infra-red and found to be identical to thestarting chloride.

EXAMPLE IV Table II Reactor Volurne15.6 cc. Reactor PackingCeramicInsulating Beads Run Number 1141- 24 25 26 27 29 30 32 33 Ave. temp, F.1,050.1 1, 052. 3 1, 050. 1, 053.1 1, 001. 951. 0 954. 0 1, 005. 0 Feedrate, cc./hr 45. 7 91. 5 244. 17. 9 12. 3 91. 5 2.01 91. Recovered C C122.78 44.40 69. 40 1. 53 11.90 92. 00 19. 70 64.75 Other 77. 22 55. 6030. 60 98. 47 88. 8. 00 80. 30 35. 25 Total product:

Propylene Trace Trace Trace 2.99 Trace Trace Trace Trace Isobutane 3. 642. 69 735 2. 17 6. 50 238 9. 1. 57 Isohutylene 7.00 2.83 20. 23 9.32.246 9.50 3.25 3,3-DMButene-1. 57. 90 38. 30 24. 70 49. 30 56. a0 6. 7745. 45 27. 00 2Mo2C4= Trace 1. 67 Trace 4. 51 1. 89 Trace 1. 08 29Is0prene 1. 34 69 606 4. 08 1. 70 Trace 90 24 2,3-DMButen 83 21 Trace 2.79 1. 67 Trace 2. 22 Trace Unidentified 1. 80 1. 90 212 1. 382,3-DMButenc-2" Trace 69 Trace 036 2. 72 528 2. 69 48 t-Butyl chloride10. 13 Vinyl chloride 3. 36 4. 38 1. 70 10.04 6.07 Trace 7. 86 2. 59Chl0ro-3,3-DMButaue 22. 78 44. 40 69. 40 1. 53 11. 90 92. 00 19. 7064.75 1$elgctivity split, mols/1OO moles Propylene Trace Trace Trace 3.39 Trace Trace Trace Trace Isobutane. 4. 2 5.26 2.53 2.46 7.93 2.98 12.7 4.78 Isobutylene 13. 78 9. 79 22. 90 11. 38 3. 0s 13. 14 9. 903,3-DMButen 78. 45 74. 75 85. 50 55. 90 68. 70 84. 68 c3. 00 32. 40 2Me2C4=. Trace 3. 27 Trace 5. 11 2. 31 Trace 1. 50 88 I Isoprene 1.81 1.35 2. 4.62 2.07 Trace 1.24 .73 2,3-DMButene-1 1. 12 42 Trace 3. 17 2. 04Trace 3. 07 Trace Unidentified .85 2. 32 2. 65 1. 91 2,3-DMButene-2Trace 1. 35 Trace 1. 22 3. 31 6. 61 3. 73 1. 46 t-Butyl chloride 13. 70Conversion 77. 22 55. 60 30. 60 98.47 88. 10 8. 00 80. 30 35.Selectivity 78. 45 74. 75 85.50 55. 90 68. 70 84. 68 63. 0o 52. 40

The data of Examples III and IV clearly illustrate that 0f theisomerization of the product indicated that the iron the presentinvention is capable of producing high selec- (probably as ferrouschloride) had an adverse catalytic tivity yields of 3,3-dimethylbutene-l with little if any efiect on the reaction so far as productionof 3,3-dimethylother C olefins such as 2,3-dimethyl butene-l and 2,3-l-butenc was concerned. dimcthyl butene-Z. A second experiment was madein which nickel shavings EXAMPLE V were used in place of iron. Theproduct was essentially In a large 3,3-dimethyl-l-butene preparation,180 lbs. 3i3'dlmethyll'butene f only trace amounts of other of 1 chloro33 dimethy1butane was passed through a C olefins. The C fraction was atleast about 95%, 3,3- Hast-Alloy 1 inch universal reactor packed withceramic dlmethyl'lbutenebeads, at a temperature of 1030 F. and an LHSVof 10. EXAMPLE VIII The product was washed with water and dilute sodiumA Sample of 2 h1oro-4,4-dimethylpentane, which had hydl'OXlde. AHaI'YSISof H18 crude product Indicated been prepared alkylat'ion tfbutylchloridewith prothe Product Contallled Olefin pylene, was pyrolyzed in a glassreactor at a temperature fAf the .ol'efilhfractlofl 0f the Product ebeen of 850 F. The conversion was 95% under these condimoved ydylstlllatlfm, i116 unconvertedchlonde Was tions and the selectivitynearly quantitative. Analysis of turned to the Crackmg feactorpP f y851bS-Of the olefin product indicated the following mixture ofcrude'olefin was recovered. Fractionation of the olefin l fi cis 4 4 1-23 7% trans, 4 4 product over maleic anhydride yielded 56 lbs. ofmaterial methypgpentene, 732% and 23 1% 4 4 1 1 boiling at a plateautemperature of 105 F. An infrared pentena analysis indicated that thepurity of the 3,3-dimethyl-1- EXAMPLE 1 P than Thls represents a 66 moleA glass reactor was packed with 20 grams of stainless percent y1e M LE Isteel No. 310 shavings and 1-chloro-3,3-dimethylbutane EXA P V wasdehydrochlorinated by passing it through the reactor A total 3350 of YPF a at a temperature of 1050 F., a liquid hourly space velocity passedthrough a small quartz reactor filled with ceram1c (LHSV) of 4 4 d apressure f 1 atmosphere S i e The r o eondltions were: temperature lesssteel No. 310 consists of 22% chromium, 22% nickel, 10650 4 LHSV Theeffluent from the reactor was 53% iron, 2% manganese and 1% silicon. Theresults stabilized on a small packed column to recover the hydroam Shownin the f ll wi bl 111 gen chloride. The olefin was then removed bydistillation. T bl III The unconverted chlon'de was returned to thereactor. a e After several passes, all but 1150 g. of the chloride hadbeen converted and a yield of 1220 g. of crude olefin of COmPOnent Gramst percent y1eld 1 approximately 85% punty was obtamed. After finalpurification, which involved fractionation over maleic H2433 M0 M9anhydride, treatment with dilute alkali and a final sodium Ispbutane1.51 1.44 treatment, a yield of 200 g. of 3,3-dimethyl-1-pentene of ggggigg f f; 3 .1; 21 iii 97% purity was obtained. geoltlelxefie3,3-d2imethyl-1-butene) 35. e ene- EXAMPL V rs en eni 1.58 1. 51 In anexperiment in which 1-chloro-3,3-dimethylbutane gfigfig gfigfigi 31 1:2was passed over stainless steel helices (type 1808) in a Neohexylchloride (unconverted) 54.50 quartz reactor, almost total conversion ofthe chloride ummethylbutenel 1309 to l fin occurred. The temperaturerange was from Total 163-16 100-03 900 F. to 1000".F. and the LHSVwas 1. Analysis of 9 b d 4 1 2 the product by gas chromatographyrevealed that the gf figgfifg gg g g l3dlmethy11cmom mane an 0 5%1118101 products were 2,3-d1methyl-l-butene and 2,3-d1- Conversionrneohex lch1oride=65.6. methyl-Z-butene. The high conversion plus theextent M012 Selectmtyto 7 The data of Table III demonstrate thesubstantial isomerization to 2,3-dimethylbutenes that occurs whenemploying contact materials having a high content of iron.

EXAMPLE X Example X was repeated employing Hast-Alloy C shavings andtemperatures of 1047" F. and 1000 F., respectively. Hast-Alloy C is anickel alloy containing 4.5 to 7% iron. The results of the runs were asfollows:

Run I II Temperature, F 1. 047 1, 000 Conversion 76. 4 67. 7 Selectivity1 67. 73. 7

1 To 3,3-dirnethylbutene-1.

The ultimate yield of the 2,3-dimethylbutene isomers was only about 3%by Weight.

EXAMPLE XII A glass reactor (114 cc.) was packed with 59 grams of Monelmetal shavings and 1-chloro-3,3-dimethylbutane was dehydrochlorinated bypassing it through the reactor at a temperature of 1025 F., a liquidhourly space velocity (LHSV) of 3.6 and a pressure of 1 atmosphere.Monel metal is an alloy consisting of 68% nickel, 31% copper and 1%iron. The results are shown in Table IV below.

Table IV Ultimate Component Grams wt. percent yield 1 Hz-Ca 2. 2. 12Isobutanm 1. 31 1. 26 Vinyl chlor 2. 73 2. G3 Isobutylene 3.80 3. 673,3-dimethylbutene-1 57. 56 55. 60 2-methylbutene2 1. 62 1. 56 Isoprene0. 81 O. 78 2,3-dirnethylbutene-1 4. 43 1. 73 2,3-dimethylbutene-2 3. 380. 59 t-Butyl chloride 0.51 0. 49 Hydrogen chloride 32.50 29. 60Neohexyl chloride (unconverted) 151. 60

Total 262. 45 100. 03

1 After correction for feed as in Table III. Conversion of neohexylchloride=40.5%. Molar selectivity to neohexene=79.6%.

The results of Examples X, XI and XII demonstrate the high selectivitytowards the neo-structured olefins for a given conversion and the lowisomerization to 2,3-dimethyl olefins obtained by alloys as contactmaterials in the process of the present invention. Such results contrastsharply with those afforded by use of the predominantly iron alloy ofExample IX.

EXAMPLE XIII 1 chloro-3,3-dimethylbutane was dehydrochlorinated bypassing it through an Inconel coil reactor at atmospheric andsuperatmospheric pressures. Inconel is an 8 alloy of Ni, 14% Cr and 6%Fe. The conditions employed and results are shown in Table V below.

Table V I II III IV 919 900 945 948 15. 7 218. 7 117. 2 G7. 2 0. 67 7.06 1. 30 3. 0G 39. 6 .21. 4 79. 3 44. 1 Molar selectivity 1 78. 2 74.455. 2 70. 5 Products, ultimate wt. Percent 1. 1. 73 4.19 2.92 6. 35 7.03 10. 10. 92 05s.. 1. 54 0.48 1. 23 1. 28 3,3-dirnethylbutene-1 54. 6351. 98 38. 70 49. 08 4-mathylpentene-1 0. 50 1. 08 5. 63 1. 642,3-dirnethylbutene-1 1. 81 2. 10 0.88 1. 22 2-rnethylpentene-1 0. 23 0.18 0.30 O. 12 2.3-dimethylbutene- 0.98 2. 50 0.65 0. (l3 Hydrogenchloride. 31.69 32. 41 32.21 31. 92 Higher boiling products 4. 40

1 To 3,3 dimethylbutene-1.

The data of Table V demonstrate that use of superatmospheric pressureshas only a small adverse etfect on the yield of 3,3-dimethylbutene-1.The small decrease in neohexene yield may be found as an increase in4-methylpentene-l (a valuable olefin monomer), vinyl chloride andisobutane.

It is claimed:

1. A process for the production of quaternary carboncontainingmonoolefins which comprises thermally dehy-' drohalogenating in thevapor form at a temperature of about 400 to 650 C. a halogenatedhydrocarbon having the structural formula:

wherein R is an aliphatic monovalent hydrocarbon radical of up to 8carbon atoms, the total carbon atoms being up to 18; R is a divalentaliphatic hydrocarbon radical of 2 to 8 carbon atoms; and X is a halogenatom having an atomic weight of 35 to 127, said dehydrohalogenationbeing conducted in a non-catalytic environment with contact with asurface containing at least about 40% nickel and a maximum of about 40%iron.

2. The process of claim 1 in which the halogenated hydrocarbon is1-halo-3,3-dialky1 hydrocarbon having a total of up to 12 carbon atoms.

3. The process of claim 2 in which the halogenated hydrocarbon is1-chloro-3,3-dimethylbutane.

4. The process of claim 1 wherein the dehydrohalogenation is conductedin a non-catalytic environment and in the presence of a nickel alloycontaining at least about 40% nickel and up to about 20% iron.

5. The process of claim 2 wherein the halo group is chloro.

6. The process of claim 1 wherein the halogen of the halogenatedhydrocarbon is on a carbon atom beta to the neo-carbon atom and thehalogenated hydrocarbon contains a total of up to 12 carbon atoms.

7. The process of claim 6 wherein the halogen of the halogenatedhydrocarbon is chlorine.

. References Cited by the Examiner UNITED STATES PATENTS 2,314,3353/1943 Frey 260677 X 2,379,372 6/1945 Mugdan et al. 260-654 FOREIGNPATENTS 736,740 9/1955 Great Britain.

PAUL M. COUGHLAN, Primary Examiner.

ALPHONSO D. SULLIVAN Examiner.

1. A PROCESS FOR THE PRODUCTION OF QUARTERNARY CARBONCONTAININGMONOOLEFINS WHICH COMPRISES THERMALLY DEHYDROHALOGENATING IN THE VAPORFORM AT A TEMPERATURE OF ABOUT 400 TO 650*C. A HALOGENATED HYDROCAROBONHAVING THE STRUCTRAL FORMULA: